Wednesday, August 31, 2011

Few of us count the number of times we chew before swallowing a morsel of food (and those who do aren’t much fun at dinner parties). Still, the age-old question remains: Can swallowing half-chewed chunks of food harm your digestive system? The answer, it turns out, is fairly sensible. You should chew your food until it becomes an easily swallowable, broken-down paste. (One rule of thumb is that the texture shouldn’t be recognizable. For example, if your potatoes still have skin on them and your broccoli still has a stalk attached, they’re not ready to swallow.)

Basic chewing has several benefits. First, it triggers activity in other parts of your digestive system, like your stomach, preparing them for the work ahead. It also helps the rest of your digestion work more smoothly, because your digestive system doesn’t need to struggle to extract the nutrients from large, tough chunks of food. Finally, chewing forces you to eat more slowly, which can reduce the chance that you’ll choke or overeat, and improves your mealtime enjoyment (and dinnertime popularity). However, there’s no reason to get obsessive about it. For example, the infamous motherly advice to count
30 chews will turn all but the most overcooked steak into something not unlike a wad of pulp from a paper mill—and who wants to swallow that?

Incidentally, extreme chewing was the foundation of a wildly popular Victorian-era diet. Horace Fletcher (also known as “The Great Masticator”) became a millionaire by championing obsessive chewing as a way to avoid constipation and other digestive ills. His strict advice was to chew each mouthful more than 30 times over the course of a half minute, and then tilt your head back to let the result trickle down your throat. You were to spit out any remaining chunks. The side effects included long meal times, dramatic weight loss, and a sore jaw.

Wednesday, August 24, 2011

The perfect complement to strength training is cardio exercise. A regimen of regular cardio exercise improves the function of your lungs, heart, and blood vessels. Over time, it gives you greater endurance for heart-pumping tasks like running, dancing, and swimming. It also reduces your risk of a whole medical manual of health problems, from diabetes to depression. It might even help you dodge a coronary catastrophe.

Getting cardio exercise is cheap and easy. You don’t need special equipment or expert advice. You simply need to do something tiring (say, jumping up and down in one spot, or dancing around in your pajamas). Do it until you start breathing heavily, and then keep at it for at least 20 more minutes. This may not sound glamorous (in fact, if you pick the pajama option, it’s downright embarrassing), but the science is sound.

The best approach to cardio exercise is to follow a regular regimen three times a week. But—surprisingly—research shows that even a single session each week has a positive effect on heart health. This finding kicks the legs out of your last good excuse to stay on the sofa.

There are two basic types of cardio exercisers—those who like slow and steady activity (say, a brisk 1-hour walk), and those who prefer shorter bursts of higher intensity work (say, 20 minutes in a hard-driving aerobics class). Both approaches are effective, and both help you burn calories and strengthen your heart. The key is to pick the right duration for your activity. If you opt for a high-intensity workout, 20 or 30 minutes is enough. A more leisurely activity requires twice that time.

Types of Cardio Exercise
If you get tired of having your friends and family laugh at your impromptu jumping jacks, you can try a more traditional form of aerobic exercise. Here are some of the most popular:

• Running. Requiring nothing more than time and a decent pair of running shoes, running is the most straightforward way to get your heart pumping. It’s also a marvelously adaptable exercise you can tailor to any fitness level. To go easy on yourself, alternate between brisk walking and a light jog. For hard-core training, maintain a steady jog with bursts of flat-out sprinting.

Running isn’t for people with joint problems because the impact of your feet striking the ground can put excess stress on your knees and ankles. However, if your joints are currently pain-free don’t worry about running. Recent research suggests that healthy runners don’t suffer from a greater incidence of joint problems than other exercisers.

• Jumping rope. Like running, rope skipping is a highly portable way to get intense aerobic exercise wherever you go. You can’t slip an entire gym in your pocket, but there’s always room for a jump rope.

• Swimming. If you have a pool handy, you can use swimming as a fullbody, low-impact form of exercise. Because it’s so gentle on the joints, many people like to alternate swimming with other types of cardio exercise to create a weekly workout program.

• Bicycling. Like running, cycling is an activity you can do either indoors (on a machine) or outside (on the street). As a side benefit, the effort of keeping yourself balanced on two wheels strengthens the muscles throughout your body.

• Cross-country skiing. It’s one of the most intense forms of full-body aerobic exercise around. Cross-country skiing has obvious disadvantages— for instance, you need a snowy trail and a lot of equipment— and newbies will find it extremely challenging. But it makes an excellent excuse to book that Nordic vacation.

• Step aerobics. Any aerobic workout routine can deliver the goods, but step aerobics stands out from the late-night infomercial gimmicks. Two decades after its creation, the basic idea (performing choreographed movements using a raised platform) remains wildly popular. Done right, step aerobics has the perfect mix of low-impact exercise and intense effort. To get started, you can try an exercise DVD. Or better yet, join a class at your local fitness club or community center.

• Gym equipment. Purists might say that a treadmill gives you all the effort of running with none of the scenery, but exercise equipment is the perfect solution for many casual exercisers. And even if the convenience of treadmills, steppers, and elliptical trainers doesn’t seduce you, you just might fall for the shiny electronic gadgetry (such as programmed courses and integrated heart-rate monitoring). If not, there’s always the wall-mounted television.

The experts agree—the best way to choose a cardio exercise is to forget about calories per minute and pick something you enjoy doing and can easily integrate into your daily routine. This gives you the best chance of maintaining a regular routine—and regularity is far more important than the type of exercise you choose.

Thursday, August 18, 2011

With its complications and uncomfortably high odds of lasting heart damage and death, a heart attack clearly tops the list of Life-Changing Experiences Worth Avoiding. But considering that heart disease is the single most common cause of death (at least in the U.S.), is it really possible to avoid cardiac calamity?

Surprisingly, there’s a lot you can do to stay out of harm’s way. Stay active, lose excess weight, and avoid stress is a good start. But if these practices aren’t doing enough in later life, it’s critically important to step up your game. In other words, forget your good intentions—your doctor needs to check your blood pressure and blood cholesterol, and use the full arsenal of modern medicine if these numbers are dangerously high. (As you’ve already seen, high blood pressure damages the delicate inner lining of your arteries. Excess cholesterol becomes trapped in artery walls, kick-starting the inflammatory process that leads to potentially dangerous plaque.)

If you’re not convinced, consider this startling statistic: a 50-year-old man who doesn’t smoke or have diabetes, and who keeps his cholesterol and blood pressure in the recommended range, has just a 5-percent chance of a serious heart event over the next half-century. But if he violates any one of these conditions, his chances rise tenfold, hitting 50 percent. Unsurprisingly, the vast majority of 50-year-olds fall into the second, far riskier category. They remain apparently healthy even as their cholesterol level and blood pressure creep up, laying the groundwork for the Big One.

A Heart Attack on a Stick
There’s one more critical step to prevent a heart attack: Stay away from cigarettes. Their effect on heart health rivals the destruction they wreak in your lungs. In fact, if you’re a chronic smoker, you’ll realize greater benefits from kicking the cigarette habit than you will from starting a hard-core workout regimen and adopting a strict health-food diet. The way cigarettes work their damage isn’t entirely clear, but smoking seems to doom your circulatory system in several ways, reducing the supply of oxygen to the heart, raising blood pressure, increasing the level of dangerous LDL, and making blood more likely to clot. Altogether, it’s a cocktail of heart trouble that’s far more potent than a daily Big Mac.

If you’re still not convinced, consider these grim facts:

» Heavy smokers have double the risk of stroke, and two to four times the risk of a heart attack.

» When a heart attack strikes, heavy smokers are nearly twice as likely to die.

» Even light smokers (those who smoke one to nine cigs a day) are at a third higher risk for a heart attack.

Wednesday, August 10, 2011

Forests that cover the northern regions of Canada, Russia, China, Scandinavia, and southern Alaska make up the boreal forests, or taiga. (Smaller areas of Japan, Korea, and Mongolia also contain boreal forest.) They include a band of growth between 45° and 57° north latitudes and form an almost continuous ring at the top of the globe. Boreal forests hold little tree diversity compared with tropical rain forests: They contain only a limited variety of coniferous trees that retain needles year-round and have a short growing season of about 130 days. Boreal forests nevertheless support extensive food webs of plants, mammals, birds, insects, and fish. They also act as a northern watershed by containing numerous lakes, rivers, wetlands, bogs, and marshes.

The boreal forests serve the Earth in the following additional ways: (1) as a carbon reservoir for storing carbon not released into the atmosphere; (2) in filtering millions of gallons of water each day; and (3) by providing resources for resident people that use the forest for hunting, trapping, and fishing. The boreal forests also contain vast potential commercial potential because of their timber, oil, gas, minerals, and hydroelectric power resources, so they have become a central point of interest of both industry and environmentalists.

Large oil and natural gas reserves under the forests of Alaska, Canada, and Russia represent the number-one threat to the future of boreal forests. Fossil fuel reserves in other parts of the world will someday run dry, and countries such as the United States desire a reliable supply of domestic fuel, which the boreal region holds. In addition to the United States, Canada, China, Russia, and Norway have all eyed their own boreal forests for oil exploration.

Global warming also threatens boreal forests because as temperatures rise the health of the cold-tolerant trees may decline, and disease and parasites gain opportunity to infect them. At the same time, warmer temperatures have already made temperate deciduous forests to the south drift north toward the boreal habitat. The warmer temperatures therefore threaten boreal growth from the south, and melting glaciers and polar ice may cause flooding from the north.

Environmental organizations have tried to protect boreal forests from the destruction that has occurred in poorly managed tropical forests. In the United States and Canada, the following organizations act as watchdogs over boreal forests by monitoring the mining, oil drilling, and logging industries and by participating in global warming talks: the Northern Alaska Environmental Center; the Sierra Club; the Nature Conservancy; the Alaska Department of Fish and Game; and the Natural Resources Defense Council; and Nature Canada.

Forests in Siberia and eastern Russia suffer added threats because of the way they have been managed, and have endured several consecutive seasons marked by wildfires, insect outbreaks, and overgrowth that keeps seedlings from maturing. Enterprises that once operated farms under socialism now own much of Russia’s forestland. These owners may view forests as a community resource to be depleted for building personal wealth without much regard for sustainable methods. For example, the Federal Forest Service of Russia for many years controlled more than 90 percent of Russia’s forests and has shown interest in conservation, but this agency also ran about 20 percent of the country’s logging. The agency furthermore has released no information on forest area land or logging activities, so environmentalist groups such as Greenpeace Russia and the Taiga Rescue Network found it difficult to design conservation action plans.

Environmentalists suspect that forest management in Russia has not been optimal. Fedor Pecar, chief of the Irkutsk airbase in Russia told Greenpeace in 2007, “This year there are more of them [fires] than in all of the previous years. One may think that now everything is being burnt off: fields and old straw. Almost half of the fires were caused by this. The villagers burn off private meadows and they are doing it recklessly and carelessly. Thus not only forest, but also buildings and houses catch fire. . . .” In 2000 Russian President Vladimir Putin signed a decree abolishing the Federal Forest Service, the only federal agency with interests in protecting the boreal forests. Fortunately, Russia’s boreal forests are very remote, and logging them would be an expense that for the present has kept them safe from large-scale destruction.

The world’s boreal forests will not be safe forever if the timber and fossil fuel industries need new places to explore. Boreal forests the world over will require careful monitoring and strong legal protections for their survival.

Tuesday, August 2, 2011

Timber companies must have roads that lead to harvesting sites to allow heavy equipment and emergency vehicles into and out of the forest. The companies usually build these logging roads themselves to meet these needs. But the road-building and the completed roads create a major disruption to forest ecosystems. In addition to the noise and dirt created during road-building, smooth-surface or packed gravel roads make forests vulnerable to the following occurrences:

At present, logging roads and helicopter landing areas built on public lands cause those lands to lose federal protection as wilderness areas. In 1997 President Bill Clinton tried to reverse this policy by passing what came to be known as the “Roadless Rule,” which authorized the U.S. Forest Service to obliterate hundreds of miles of abandoned logging roads and halt construction on others. At the time, Forest Service officer Bob McDowell in Lake Tahoe, California, told the Tahoe Daily Tribune, “The kinds of roads that we will obliterate are the roads that don’t go anywhere—old logging roads and landing areas. The ultimate goal is to re-contour some roads, to make the road bed disappear.” The recovery of the land under the Roadless Rule has progressed very slowly, and thousands of miles of abandoned logging roads remain in North American forests. Some states, such as Idaho and Alaska, have challenged the Roadless Rule for putting too severe a restriction on their forest management. For example, at the close of 2003, Alaska had successfully won the right from the USDA and the Department of Justice to exclude the Tongass National Forest from the Roadless Rule.

The effect of abandoned and overgrown roads has not been determined. Scientist Eric Sanderson of the Wildlife Conservation Society said in 2005, “Roads are terrific at providing human access to areas, but unfortunately they bring with that access a host of ecological problems.” The timber industry countered that forest roads were necessary to serve local communities in times of wildfire, meaning an out-of-control fire. In 2005 President George W. Bush did away with the Roadless Rule to allow greater access for mining and logging in the nation’s forests. Chris West spoke for the American Forest Resource Council in support of the White House’s decision and to calm the public’s fears over road expansion: “Despite the environmental rhetoric, chain saws, bulldozers and drilling rigs are not gassing up to enter roadless areas.” The case study “Boreal—Earth’s Northern Woods” discusses how roads and other human activities in the forest have kept this debate alive.

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In its broadest sense, science (from the Latin scientia, meaning "knowledge") refers to any systematic knowledge or practice. In its more usual restricted sense, science refers to a system of acquiring knowledge based on scientific method, as well as to the organized body of knowledge gained through such research.

Fields of science are commonly classified along two major lines: natural sciences, which study natural phenomena (including biological life), and social sciences, which study human behavior and societies. These groupings are empirical sciences, which means the knowledge must be based on observable phenomena and capable of being experimented for its validity by other researchers working under the same conditions.